EGFR and colorectal carcinoma: Moreover, the upstream signal regulation of KRAS is interrupted by aberrant activation of the KRAS pathway, which results in resistance to receptor tyrosine kinase (RTK) inhibitors, such as monoclonal antibodies against epidermal growth factor receptor (EGFR) (cetuximab and panitumumab), in patients with KRAS-mutant CRC [10, 11].